1. Field of the Invention
The present invention relates to Internet communications systems, and more particularly to an asymmetrical hybrid satellite-terrestrial communications network for such systems.
2. Background and Prior Art
Abbreviations used below
ATM--asynchronous transfer mode PA0 BGP--border gateway protocol PA0 CIR--committed information rate PA0 DLCI--data link connection identifier PA0 EIR--excess information rate PA0 EISP--Europe-based Internet service provider PA0 ERTR--Europe-based Internet service provider US gateway router PA0 FRS--frame relay switch PA0 IP--Internet protocol PA0 IPX--a Novell network protocol PA0 ISP--Internet service provider PA0 LM--link management PA0 NAP--network access point PA0 POP--point of presence PA0 PVC--permanent virtual circuit PA0 REP--reply packet PA0 REQ--request packet PA0 SCPC--single channel per carrier PA0 URTR--router of US Internet service provider cooperating with Europe-based Internet service provider router PA0 USISP--US Internet service provider PA0 VSAT--very small aperture terminal
The Internet is a collection of independent computer networks, which communicate with each other using standard communication protocols. By using such standard protocols, any user on any network can access any server on any other network on the Internet, subject to security considerations.
Entry into the Internet is furnished by Internet Service Providers (ISPs). ISPs operate networks that connect with each other at network access points (NAPs).
A typical network includes communication links and routing devices known as routers. A router includes tables which correlate addresses with destination information. Routing protocols are used to keep the information in the routing tables up to date to ensure that the information tables contain accurate information. Information is transmitted between NAPs in the form of individual data packets. Each packet contains an embedded source and destination address to which the packet is routed across the networks.
A typical Internet transaction involves a small amount of data in the form of a request from a user or client, and a much larger amount of data in the form of a response from the server of the content provider containing the requested information. The traffic imbalance represents a substantial waste of bandwidth in asymmetric terrestrial link.
Many Internet users are limited to voice grade terrestrial communication lines with dial-up access, in which bandwidth is limited to 28 kbps and 56 Kbps. Where faster data rates are available, they are very expensive. ISPs have been known to undersize their banks of telephone modems to reduce costs, and oversubscribe their service to increase revenues. This results in the inability of users to connect to the ISP during peak hours of usage and the tendency of users to stay connected longer once access is gained, for fear of not being able to get back on line, resulting in more Internet congestion.
One situation in which unequal data streams flow between requesters and Internet servers is that of Internet usage, called Web traffic, by users in Europe. Today in a nominal European country, 25% of requests on the Web are for content from within the country, 25% are for content that resides in the rest of Europe, and the remaining 50% is for content from the rest of the world, predominantly the United States. Most of this international traffic is routed via a Internet exchange point such as MAE-East, physically located near Washington D.C. When a user in Europe requests a Web page or file located in the United States, a small amount of data flows to the United States in the form of the request, and a relatively large data stream constituting the responses to requests flows from the United States to Europe. Currently, the amount of data transmitted to Europe is three to five times that transmitted from Europe to the United States.
For purposes of the present description, remote ISPs are described as not being conveniently connected to the Internet. This refers to the condition of there being some inherent problem with terrestrial backbone infrastructure to meet the explosive growth of Internet traffic. United States ISPs in the present example are referred to as high volume ISPs in that their terrestrial backbone infrastructure provides capacity, connectivity and peering for Internet traffic.
The present system may in fact end up being used between infrastructures that are each rather well developed. This terminology is used simply as a context through which the present invention is described.
It is desirable to provide a system which maximizes use of available bandwidth, provides for asymmetrical use of satellite and terrestrial links and efficiently handle packets of data. The concept of asymmetrical bandwidth in a hybrid communications network using satellite and terrestrial links is known. In a known prior art system, a desktop client launches and Internet application on an IPX network. The client connects to an Internet gateway to a Server using technology providing traffic management and asymmetric routing. The user sends a request to a control center over a telephone connection with the return IP address of the customer's satellite dish. The response to the customers request is beamed to one of the satellites which beams the response back to the customer dish. The dish forwards a response to a server to an IP gateway which sends the response back to the desktop via IPX. This system meets its intended objectives. However, the present invention is intended to meet different and further objectives.